mozglue/build/ppc.cpp

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this
   3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 /* compile-time and runtime tests for whether to use Power ISA-specific
   6  * extensions */
   7
   8 #include "ppc.h"
   9 #include "mozilla/Unused.h"
  10
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13
  14 #if defined(XP_LINUX)
  15 // Use the getauxval() function if available.
  16 // ARCH_3_00 wasn't defined until glibc 2.23, so include just in case.
  17 #  include <sys/auxv.h>
  18 #  ifndef PPC_FEATURE2_ARCH_3_00
  19 #    define PPC_FEATURE2_ARCH_3_00 0x00800000
  20 #  endif
  21 #endif
  22
  23 const unsigned PPC_FLAG_VMX = 1;
  24 const unsigned PPC_FLAG_VSX = 2;
  25 const unsigned PPC_FLAG_VSX3 = 4;
  26
  27 static signed get_ppc_cpu_flags(void) {
  28   // This could be expensive, so cache the result.
  29   static signed cpu_flags = -1;
  30
  31   if (cpu_flags > -1) {  // already checked
  32     return cpu_flags;
  33   }
  34   cpu_flags = 0;
  35
  36 #if defined(XP_LINUX)
  37   // Try getauxval().
  38   unsigned long int cap = getauxval(AT_HWCAP);
  39   unsigned long int cap2 = getauxval(AT_HWCAP2);
  40
  41   if (cap & PPC_FEATURE_HAS_ALTIVEC) {
  42     cpu_flags |= PPC_FLAG_VMX;
  43   }
  44   if (cap & PPC_FEATURE_HAS_VSX) {
  45     cpu_flags |= PPC_FLAG_VSX;
  46   }
  47   if (cap2 & PPC_FEATURE2_ARCH_3_00) {
  48     cpu_flags |= PPC_FLAG_VSX3;
  49   }
  50 #else
  51   // Non-Linux detection here. Currently, on systems other than Linux,
  52   // no CPU SIMD features will be detected.
  53 #endif
  54
  55   return cpu_flags;
  56 }
  57
  58 namespace mozilla {
  59 namespace ppc_private {
  60 bool vmx_enabled = !!(get_ppc_cpu_flags() & PPC_FLAG_VMX);
  61 bool vsx_enabled = !!(get_ppc_cpu_flags() & PPC_FLAG_VSX);
  62 bool vsx3_enabled = !!(get_ppc_cpu_flags() & PPC_FLAG_VSX3);
  63 }  // namespace ppc_private
  64 }  // namespace mozilla